One-step self-assembled synthesis of CuO with tunable hierarchical structures and their electrocatalytic properties for nitrite oxidation in aqueous media

► A simple method to synthesize CuO assemblages with tunable hierarchical structures. ► The secondary nanostructures can be modulated by selecting preparative parameters. ► The catalytic properties of the as-obtained hierarchical structures were evaluated. ► The higher hierarchical structures exhibited excellent electrocatalytic activity.